Construction of Electrochemical Aptasensor Based on Sandwich Carbon Nanotube/Gold Film for Detection of Bisphenol A

An electrochemical aptasensor for detection of bisphenol A (BPA) was developed in this work. Disposable gold-film working electrode was modified with gold-coated multi-walled carbon nanotubes to form a sandwich structure, which could greatly enhance the surface area of the working electrode and electronic transport. TMB (3,3',5,5'-tetramethylbenzidine), acting as signal molecule, was intercalated into the immobilized aptamer to form a ssDNA-TMB complex. In the presence of BPA, the immobilized aptamer would have a conformational change, leading the intercalated TMB to be released from the complex. As a result, the electrochemical signal of the intercalated TMB was decreased. The change of peak current measured using differential pulse voltammetry was linearly correlated with the natural logarithm of concentration of BPA from 0.05 nmol/L to 500 nmol/L. The limit of detection was 43 pmol/L. The recoveries in real samples at different spiked levels were in the range of 88.9% - 110.2%, and the relative standard deviations ( RSDs) were 2.7% - 9.0%. The proposed aptasensor here was simple, efficient and suitable for field testing, showing good potential for the supervision of consumer products safety.